Tufftride is a salt bath nitriding process by Dufferit in Germany, and has been in use in a wide range of industries. The process is carried out in a subcritical (510~580oC) bath, where nitrogen and small amount of carbon are diffused into the surface of component and conform e-iron compound on surface layer of component. The hardness of compound layer, ranging from 400 to 1200 HV depending on the base material used, is responsible for fatigue, wear and galling resistance
Examples of Application
Hot work tools : Forging, extrusion, die casting mould Cold work tools High speed steel tools Crank shaft, Cam shaft Cylinder liner, block & head Gears Diesel engine valve Plastic injection screw & barrel Food processing equipments & tools
QP is the liquid soft nitriding process applicable for any kind kind of steel. Process is very quick compared with the other nitriding process in case of both small or large lot production. High surface hardness obtained by theis process, makes tool life longer. QPQ is an oxidizing cooling process by using special salt of AB1, after QP process is done. By applying QPQ treatment, corrosion resistance will be much improved along with wear resistance
Hardness and Case depth
Nitrided layers by Tufftride process consists of white layer (compound layer) and diffusion layer Characters of surface of product is mainly affected by white layer. Surface hardness and thickness of both layers depend on the material used and on nitriding duration. Figures right are quoted from Bohler book.
Our Facilities
QP TF1 SALT BATH Ø 500 x 750 mm Ø 710 x 1500 mm Ø 1000 x 1500 mm QPQ AB1 SALT BATH 50x1000x1400mm Ø 1000 x 1500 mm
Corrosion Resistance by QPQ
By applying Tufftride QPQ process, corrosion resistance is dramatically improved.      To determine the corrosion resistance of sample and component, a salt spray test (German Standard DIN 50021) and a total immersion test (DIN 50905) are often carried out.      The under figure shows the result of a salt spray test by a 5% salt solution at 35o C on both hard chrome plated piston rod and Tufftride QPQ treated carbon steel bars. After 40 hours, the first corrosion spots occurred on the chrome plated piston rods. After 180 hours, the chrome plated rods showed very heavy corrosive attack over a large area. The QPQ treated rods, however, showed no sign of corrosion.
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